Graphene-creating boffins have discovered a new purpose for the wonder material - a teeny-tiny distillery.
A team led by one of the Nobel prize-winning scientists who first made the world's thinnest and strongest material have now found out that graphene can stop air and other gases, but it lets water right through.
Naturally, …

Well certainly

Water purification

Firstly, baffled as to how it would let water through but not helium through, given the size difference at play (only thought coming to mind is dipole nature of water?), but if this membrane does just let water through, and not anything else commonly found in drinking water, water purificaion options are surely about to get a boost?

That said distillery option is also pretty intriguing - I believe home distilleries were made illegal for their potential to go 'boom' - a flame/heat/pressure chamber free solution should therefore become viable...??

ilegal Stills

Home distilling was made illegal because of the lucrative tax levied on spirits. The reason given might have been health and safety but money was always the prime mover.

I was under the impression that helium always leaked because it was small and would always find any faults or interstitial cavities. If the graphene layer is a perfect lattice then there are no gaps as proven by its ability to block helium. Water molecules must therefore be 'passed' through the graphene by some sort of active process like a molecular level machine or catalyst.

"how it would let water through but not helium "

It's not clear to me how the layers are orientated bu it looks as though the graphene sheets are stacked "vertically" |||||| so that the water has to move along between the sheets. If these have hydrophilic groups and have dimensions that just allows water to move through the spaces then other materials may well have problems as there will be a strong tendency for water to fill the spaces and repel any other molecules. In this situation the water will behave quite differently to bulk water - it'll be more like a sloppy ice where every water molecule that evaporates from the low humidity end will need to be replaced from the high end to maintain the energetics.

Home brewing question

1 l/hm^2

A liter-per-hour-per-square-meter of graphene-mat surface actually could work quite nicely for personal or household water filtering. In areas where clean water is hard to come by, if the graphene material can be produced cheaply enough, you could build a decent home water distillation system out of that.

According to a couple of references I just checked, it looks like an adult in hot, arid conditions performing a mix of moderate and heavy exertion needs around 2-3 liters of water per day. I have no idea if that's at all reliable, but if it is, then a system producing 1 liter per hour could handle the drinking-water requirements of 8 adults. Even when we allow for cooking water and a ration of cleaning water, that looks reasonable for a household.

Similarly, it'd probably work nicely for applications like camping, since you should be able to fold the mat for transportation.

fresh water

I wonder if it lets Na+ through?

there would be a huge market for potable water, for dry countries and for ships, hikers etc. At present they pump water through polythene, which takes a lot of effort and energy. sounds like it just pours through this wonder-stuff.

The phrase "over time"

does not, to me, indicate that it pours or even drips. But letting only pure H2O through sounds like a good thing. Just remember that for drinking you then need to add a few minerals, but those are easy to carry with you in powder or tablet form.

D2O

selectively allows H2O to pass

I guess it well might. Even chemistry is different with deuterium. The rates of reactions are generally slower and drugs with a hydrogen replaced by deuterium at a point of metabolism are usually metabolised significantly more slowly.

desalting water

I'm guessing it could desalt water. However, we already have pretty decent (and much cheaper) filters to do that. The problem is pushing the water with enough pressure to get usable volumes on the other side (and using a filter able to withstand the pressure; a test that graphene is likely to fail.)

Flying cars?

Waters weird

as I vaguely recall from 30 years ago. You'd *think* it would be ionically bonded, but IIRC it's actually weakly covalent, which is why it has some odd properties which are essential to life (why do you think the first indication of life astrobiologists use is liquid water). Also remember the "anomalous expansion of water "as it cools through 4C ?

@JimmyPage

That's not even the start of it. Water has a whole load of anomalous properties, due to various things, such as hydrogen bonding, its dihedral angle, dipole and the unbonded lone-pairs of electrons on the oxygen atom.

But what about Helium?

Helium is atomic number 2, the second smallest element in existence besides Hydrogen at 1. It's atomic weight is a mere 4. And it's a noble gas, to boot, so it normally exists atomically. How can anything that allows water (which contains the much-larger oxygen atom--atomic number 8, weight 16) not allow helium. It can't be anything like a filter of sieve, since helium is smaller than water.

Always too much water in the way.

Gaps in the membrane are exactly "one water wide". There's NEVER any room for anything else. As soon as there's room for a fresh water molecule at a gap, it displaces anthing which might physically occupy the space. He (and everything else) gets left behind.

%age measurements of alcoholic beverages are the %age by volume of alcohol in them. Thus 300% a) isn't possible and b) would kill you if it were.

Degrees of proof orginally measured the effect when gunpowder is soaked in whatever it is. If the gunpowder just still burns, you have 100 degrees of proof (which is a shade under 60% by volume alcohol). 300 degrees would remove your eybrows when you lit the gunpowder (and is also impossible, being about 175% abv alcohol if my maths is correct).

Stereotypically, Yank "proof" differs from British "degrees of proof".

Beer is measured by Original Gravity and you should be aiming for about 1100 for something really lethal and yet still drinkable.

It's Friday and you presented the opportunity to look again at booze strength measures, what did you expect?